specialix: fix compiler warning on specialix_pci_tbl

Annotate specialx_pci_tbl as '__used' to fix following warning:

  CC      drivers/char/specialix.o
drivers/char/specialix.c:2358: warning: ‘specialx_pci_tbl’ defined but not used

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Roger Wolff <R.E.Wolff@BitWizard.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>